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  • Northern Black Widow - (Lactrodectus variolus)

    Northern Black Widow - (Lactrodectus variolus)

    The Northern Black Widow shares a lot in common with its southern cousin, including an increasingly painful bite and an urgent visit to the doctor.


    Staff Writer (8/24/2017): The glossy, black abdomen of the Northern Black Widow is dotted with large red circles on the dorsal (back) side and a split, or broken, hourglass on the ventral (belly) side. That separation of the top and bottom the the hourglass is different from the solid, one-piece hourglass seen on the more widely recognized Southern Black Widow. Only females are harmful; males are slightly different in pattern and are considered harmless. The venom of both species' females is toxic, but the Northen Black Widow's is less so.

    Mortality from a bite by a Northern Black Widow is about 1% of all victims, with most of those fatalities being small children. Any bite from a Northern Black Widow merits a visit to a physician as it is difficult to gauge how toxic the spider's venom is at the time of the bite and how the individual will respond to it. (i.e. A spider that recently emptied venom into an insect will have less venom in a bite soon after that.) All bite victims experience pain immediately and it increases in intensity for hours afterward. It usually subsides in a day. Other symptoms include sweating, fever, nausea, rapid heart rate and weakness. A physician can help ease the immediate discomfort a victim feels and monitor the patient for other symptoms.

    This species of spider forms tangled, messy webs in woodlands, stone and wood piles and undisturbed corners of sheds, garages and other shelters outside. They are not aggressive and do not actively seek to bite people. They are shy and more apt to try and hide. If startled or threatened, which can happen when a person suddenly turns over the log or stone they are on, they bite in defense. Sightings of this species is somewhat rare as they are active at night and less likely to be seen. If spotted, treat them as a dangerous spider and keep your distance.


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    Details of the:
    Northern Black Widow


    Category: Spider
    Common name: Northern Black Widow
    Scientific Name: Lactrodectus variolus

    Taxonomy:
      Kingdom: Animalia
       Phylum: Arthropoda
        Class: Arachnida
         Order: Araneae
          Family: Theridiidae
           Genus: Lactrodectus
            Species: variolus





    Size (Adult, Length): 4mm to 11mm (0.16in to 0.43in)

    Identifying Colors: black, red, orange, white

    Additional Descriptors: biting, painful, venomous, harmful


    North American Reach (Though Not Limited To*): Connecticut; Delaware; Maine; Maryland; Massachusetts; Michigan; New Hampshire; New Jersey; New York; Ohio; Pennsylvania; Rhode Island; Vermont; Virginia; West Virginia; Wisconsin; Ontario; Quebec


    * Keep in mind that an insect's reach is not limited by lines on a map and therefore may appear in areas/regions/states beyond those listed above.





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